[25stevem]

That trade off sounds right.
You gave up some down low torque / bottom end snap that made the start of a burn out easy for more torque where the motor spends its most reving time in during a pass down the track.

It’s aways the average numbers that mean more even in heads up racing!

[Formulajones]

Originally Posted by scott70

Well I tried the 11/16" thick 4 hole spacer last night. Between the gaskets added up the 4 hole was only 1/8th inch thicker than the open divided 1/2" spacer. It was about the same performance. Mph and 60fts were the same. For the hell of it I took out the spacer completely and just used a stock 1/8th gasket for the last 2 passes. 60ft was immediately better by a tenth on both passes. Also coming up the return road and flooring it in 1st gear I could tell it had more pull from a low rpm.Mph was the same through out the night. Launching at a low rpm with my m21 and 3.31 gears it liked it...pulled through 1st gear gear quicker. It was weird though as I usually do a little standing burn out I had to push more on the throttle to get to 4000rpm while heating the bfg's. Did it both times.

With a auto trans and a little converter this all probably wouldn't mean anything. It would drive through this low end stuff quickly.

Awesome feedback. You are exactly right. Testing this stuff with a stick, especially one that is limited in it's 1st gear multipication is where it will show itself and why I was hoping you would do this. An automatic with a decent converter simply drives right through it.

Question, I assume the stock 1/8" gasket was the open style? Since the intake is open with a divider.

Next time at the track with mine I'll try just a gasket, which will lower the carb a 1/2" and give me more room to raise the air cleaner lid with a slightly taller filter. As of right now in it's factory configuration the lid is only 1/4" above the carb air horn and that's not doing me any favors, and it's too close to the hood to do anything with it.

[25stevem]

Hey gang, don’t forget that with a Q-jet since it has no lead in radius on the secondary side air horn like a Holley that the radius / lead in taper that the cleaner base plate forms is also very important!

Here is some guide lines that should give you thought as to what might be able to be done.

These numbers are percentage of flow gain over just a straight edge of a lead in tube.

Number 11 looks like it’s doable with body putty or clay epoxy mod’s to a air cleaner base.

[scott70]

Originally Posted by Formulajones

Awesome feedback. You are exactly right. Testing this stuff with a stick, especially one that is limited in it's 1st gear multipication is where it will show itself and why I was hoping you would do this. An automatic with a decent converter simply drives right through it.

Question, I assume the stock 1/8" gasket was the open style? Since the intake is open with a divider.

Next time at the track with mine I'll try just a gasket, which will lower the carb a 1/2" and give me more room to raise the air cleaner lid with a slightly taller filter. As of right now in it's factory configuration the lid is only 1/4" above the carb air horn and that's not doing me any favors, and it's too close to the hood to do anything with it.

The gasket I used was a 4 hole...unmodified. I do have a even thicker open qjet gasket but didn't take it with me. The better 60ft but same mph is telling me I might of lost a little upper rpm hp. I only shift at 5300. Even on the highway flooring it from 60 mph to 80 ir felt like it pulled harder with the 1/2" spacer over the no spacer but that could of been my imagination. With the 1/2" spacer I was using a 1/8th " gasket and a thinner one. With the 11/16" spacer I was using 2 thin ones.

[Formulajones]

Originally Posted by scott70

The gasket I used was a 4 hole...unmodified. I do have a even thicker open qjet gasket but didn't take it with me. The better 60ft but same mph is telling me I might of lost a little upper rpm hp. I only shift at 5300. Even on the highway flooring it from 60 mph to 80 ir felt like it pulled harder with the 1/2" spacer over the no spacer but that could of been my imagination. With the 1/2" spacer I was using a 1/8th " gasket and a thinner one. With the 11/16" spacer I was using 2 thin ones.

On mine I run a 1/2" wood spacer that I made, with an opening between the secondaries. Either side of that spacer is just a paper thin gasket cut to fit.

If I remove the 1/2" wood spacer I'd likely replace it with one of the 1/4" thick open gaskets, not for the space, but to act more like an insulator. I'm always insulating the carb from heat with at least one of those gaskets, or a wood or phenolic spacer etc...and since I daily the car everywhere, I'm not looking to create heat soak drivability problems.

What I'm thinking is that switch would give me more room to play with the air cleaner lid. Not an issue on your car but on my firebird with the stock RA setup it's tight to the hood, just the way it is, and I've never liked the fact that the lid is nearly right on top of the choke horn. Not a great idea but they didn't have much to work with.

I may not find a darn thing with those small changes but I'm always willing to try stuff, it's part of the fun. Your feedback has me wondering if there is something there.

[ponjohn]

I was under the impression that the SD intake had runner work done as well, not just plenum?

[scott70]

Originally Posted by ponjohn

I was under the impression that the SD intake had runner work done as well, not just plenum?

Mine is not a duplicate of the SD intake. I just did the top ...it already had a port match. I'm sure the cnc version opens up the ports some. I thought the mod I did alone would improve power but I didn't see that at the track
And then I started playing with spacers My best run last night was almost the exact run in my sig. It seems the tallier I go the more it hurts low rpm trq

[JUDGE3]

top off the mod by removing the heat crossover.

pic of my cast iron manifold that I cut out the heat crossover.

[DaleO]

Originally Posted by JUDGE3

top off the mod by removing the heat crossover.

pic of my cast iron manifold that I cut out the heat crossover.

Do you have a weight saving estimate?
Thanks

[1968GTO421]

Originally Posted by JUDGE3

top off the mod by removing the heat crossover.

pic of my cast iron manifold that I cut out the heat crossover.

Something I've thought of doing. How did you fill the heat riser hole in the cylinder head?
Thanks.

[Steve C.]

Hurricane Intake Manifold ?

https://butlerperformance.com/i-2445...tegory:1234847

Same height as a factory intake.



.

[b-man]

Originally Posted by DaleO

Do you have a weight saving estimate?
Thanks

About 12 pounds removing both exhaust and coolant crossovers and substituting an aluminum coolant crossover.

Check out post #14 in this thread:

https://forums.maxperformanceinc.com...d.php?t=772223

[JUDGE3]

Originally Posted by 1968GTO421

Something I've thought of doing. How did you fill the heat riser hole in the cylinder head?
Thanks.

weight was of zero concern. so I have no idea. removed it for keeping the intake/fuel mixture cooler. plus looks cool and makes folks take a second look when noticing its cast iron. never got around to separating the water crossover because I changed intakes. was going to do the mod discussed here (saw it in Jim Hands book) but again, I changed intakes and moved to a holley.

no need to fill the heat risers in the heads, I fabbed the block off plates to cover that. make em wider etc depending on the heads your using. I used aluminum for the block off plates. made mine but you used to be able to buy em.

[scott70]

Originally Posted by JUDGE3

top off the mod by removing the heat crossover.

pic of my cast iron manifold that I cut out the heat crossover.

Hmmmm....interesting. I had SD fill my cross overs in the heads.

[scott70]

Guess Ill sell that 11/16" spacer I just bought...dont believe Ill ever use it.

[scott70]

https://youtu.be/j1xRw6iOMQw

https://youtu.be/G28StWtjYpo

Daytime is 1st run,,the dark one is the last run with no spacer. Hard to hear but you can hear it goes through 1st gear quicker with the no spacer.

[78w72]

Originally Posted by Steve C.

Hurricane Intake Manifold ?

https://butlerperformance.com/i-2445...tegory:1234847

Same height as a factory intake.



.

that intake looks like another copy of the original tomahawk intake. do you know if its any different than the previous versions? butler says its the same casting as the original performance products modeled after the SD ported holley street dominator. "Same design and casting as the original Performance Products PPR-56031 modeled after the Holley Street Dominator Intake"

if its the same intake, lots of other places sell it for a lot cheaper than butlers price. i have one of the polished versions ive been considering trying but doubt it will run any better than my SD ported HO intake. speedway & a few others have these for less than $200 shipped.

https://www.ebay.com/itm/26411819528...Bk9SR7yo7-HzYA

[Steve C.]

Personally I cannot speak for the other companies' products that have been involved with the Tomahawk intake. I bought one of the first production units as Butler describes. I suspect there is little if any difference between them.

While the Tomahawk intake was in fact patterned from a HSD intake modified by Dave Bisschop the production Tomahawk 'as cast' needed quite a bit of work if using taller ports like I used on my Edelbrock heads.
For sales reasons on the production Tomahawk they took the nice Dave Bisschop designed runners and contoured them down VERY small at the port openings so that they would fit the small sized factory D-port heads.
The plenium needed some work as well.

Related, my Dave Bisschop modified HSD intake was a piece of artwork and performed very well. On dyno testing with my old street 462 motor this modified HSD intake made 476.2 ft.lbs. torque at 3500 rpm. Peak torque was at 4600 rpm with 589.0 ft.lbs. torque. It made peak power at 5600 rpm with 589.4 horsepower. At the same time we tested a Victor intake and the Tomahawk made only 10.6 less horsepower at peak. And at peak torque rpm it made about 6 ft.lbs. less torque than the Victor.

One could do the same thing with a Tomahawk intake.



.

[Skip Fix]

if its the same intake, lots of other places sell it for a lot cheaper than butlers price. i have one of the polished versions ive been considering trying but doubt it will run any better than my SD ported HO intake.
All depends on HP level. Steve's intake dynoed the same as my modified Torker II on my 525 on the dyno 570 hp based on mph 455. My previous 455 that ran the same an HO intake lost a lot when I swapped the same T2 on it! The T2 picked up a BUNCH. on a low 11 high 10 3800lb car.

[Cliff R]

I've dyno and drag strip tested the Tomohawk intake. It absolutely REQUIRES at least a 1" spacer to perform like it should. Both on the dyno and at the track it did not fair well without one.

Not sure why and never much cared to chase that deal around much because it's too tall in that configuration for many of the applications it would end up on.

So if you have room for one plus a 1" spacer and don't have to use a drop-base air cleaner or move the air cleaner lid too close to the carburetor, it might be something to look at. Even with that said it wouldn't even be on my list for an engine making less than about 500hp.......FWIW.......